control/controlhttp: don't link ts2021 server + websocket code on iOS

We probably shouldn't link it in anywhere, but let's fix iOS for now.

Updates #13762
Updates tailscale/corp#20099

Change-Id: Idac116e9340434334c256acba3866f02bd19827c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

control/controlhttp/server.go

@@ -1,6 +1,8 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
+//go:build !ios
+
 package controlhttp
 
 import (

tstest/iosdeps/iosdeps_test.go

@@ -17,6 +17,8 @@ func TestDeps(t *testing.T) {
 			"testing":                    "do not use testing package in production code",
 			"text/template":              "linker bloat (MethodByName)",
 			"html/template":              "linker bloat (MethodByName)",
+			"tailscale.com/net/wsconn":   "https://github.com/tailscale/tailscale/issues/13762",
+			"github.com/coder/websocket": "https://github.com/tailscale/tailscale/issues/13762",
 		},
 	}.Check(t)
 }